Question

25. A motorist travelling at 13 ms-l approaches traffic
lights, which turn red when he is 25 m away from
the stop line. His reaction time (i.e. the interval
between seeing the red light and applying the
brakes) is 0.7 s and the condition of the road and his
tyre is such that the car cannot slow down at the rate
of more than 4.5 ms-2. If he brakes fully, how far
from the stop line will he stop and on which side of it. ​

Answer 1

Answer: 17 m from the stop line not crossing the traffic lights

Explanation: the car will decelerate between time interval .7s at 4.5 ms^2.

so distance covered= 8 m formula used s=ut=1/2at^2

8m is less than 25m so 25-8=17m from the sto line.